PWM: Pulse Width Modulation is the process of modulating an analog signal usually voice frequency in the form of variation of pulse width proportional to the voice (or signal) amplitude. The voice frequency is modulated on an internally generated carrier wave. The reconstruction process of this wave is by demodulating and original voice signal is recovered. This trainer requires an external function generator with 1 KHz frequency and 1 V P toP signal strength. Using a dual beam oscilloscope it is possible to observe the input signal, modulating signal and demodulating signals.
PAM: Pulse amplitude modulation is a type of modulation is used as the first step in converting an analog signal to a discrete signal or in cases where it may be difficult to change the frequency or phase of the carrier. In this case the carrier is a pulse train rather than a sine wave and the spectrum of the carrier consists of several components at nwc = 2np/T where T is the time between pulses.
Using this trainer it is possible to observe the modulated PAM signal and demodulated message signals on the Oscilloscope. It is necessary to study the effect of sampling pulse duration, sampling rate on the PAM signal and on the demodulated signal. Be sure to reduce your sampling frequency such that your sampling frequency is below Nyquist rate.
PPM: Pulse position modulation makes use of PWM signal generated during PWM setup as input for modulation purposes.
This is a 3 in 1-modulation trainer. This trainer is intended to study the basic principles of Pulse Modulation techniques. This provides a unique opportunity to construct a complete modulation setup required in a communication system. This can be best studied and experimented in the audio range. This requires two independent external function generators as necessary sources for generating carrier and signal. This trainer has all the necessary active and passive components required to perform the experiments, and built-in power supply. The output waveforms can be monitored on an external CRO. You need an external function generator, a pulse generator operating in the range of 100 Hz to 100KHz, and an Oscilloscope for observing the waveforms.
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